Events at Physics
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Events on Thursday, November 17th, 2011
- R. G. Herb Condensed Matter Seminar
- Resonant Passage of Spin States in a Triple Quantum Dot
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Xuedong Hu, University of Buffalo
- Abstract: Experimental and theoretical research on spin qubits in quantum dots are progressing toward systems with multiple spins in multiple dots. Among the many quantum information processing tasks that can be accomplished by such a multi-qubit system is the coherent transfer of quantum states on chip, which is an essential capability of a practical quantum computer. In this talk I will discuss our recent work on the physics of adiabatic quantum teleportation in a triple dot system. In particular, we show that a teleportation process over a three-spin chain can be mapped exactly onto two parallel and coherent adiabatic passages, one for each spin orientation. When the time evolution is not adiabatic, we find that the fidelity of information transfer displays a strong oscillatory behavior, and it is possible to have high fidelity when the switching frequency of the qubit interactions is a subharmonic of the characteristic energy splitting of the three-spin system. This resonant operation of an adiabatic passage protocol of spin states is both fast and robust, and points to a new way to perform other quantum gates.
- Host: Coppersmith
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Magic, precise, and electroweak
- Time: 2:30 pm
- Place: 4274 Chamberlin Hall
- Speaker: Andrei Derevianko, University of Nevada-Reno
- Abstract: Precision timepieces are marvels of human ingenuity. Over the past half-a-century, precision time-keeping has been carried out with atomic clocks. I will review a novel and rapidly developing class of atomic clocks, optical lattice clocks. At their projected accuracy level, these would neither lose nor gain a fraction of a second over estimated age of the Universe. In other words, if someone were to build such a clock at the Big Bang and if such a timepiece were to survive the 14 billion years, the clock would be off by no more than a mere second. I will also talk about the next frontier: nuclear clock.
In the second part I will overview atomic searches for new physics beyond the Standard Model of elementary particles. I will report on a refined analysis of table-top experiments on violation of mirror symmetry in atoms that sets powerful constraints on a hypothesized particle, the extra Z-boson. Our raised bound on the Z' masses improves upon the Tevatron results and carves out a lower-energy part of the discovery reach of the Large Hadron Collider.
- Host: Mark Saffman
- Graduate Introductory Seminar
- Condensed Matter Experimental Seminar
- Time: 5:30 pm
- Place: 2223 Chamberlin Hall
- Speaker: Eriksson, Himpsel, Lagally, McDermott, Onellion, Rzchowski, Winokur